MOMENT-ROTATION BEHAVIOR OF BASE-PLATE CONNECTIONS IN LOW-RISE METAL BUILDINGS

In designing low-rise metal building systems, column-base connections are commonly assumed to be pinned with no rotational stiffness for both serviceability and strength limit states; however, practical experience indicates that even base connections that are designed to be pinned have a non-negligible rotational stiffness. The excess displacement resulting from this assumption is addressed by increasing the flexural stiffness of the frame members, which unnecessarily increases the cost of low-rise metal buildings. There is a distinct lack of design guidelines and experimental data to support the use of non-zero rotational stiffness at the so-called pinned column bases. The objective of this research is to quantify the rotational stiffness as well as the strength of column base-plate connections in low-rise metal building systems by testing eight full-scale base-plate connections with varying base-plate dimensions, number of anchor rods, anchor rod diameters and gage distances, and taper of the column sections.